The invention relates to syringes suited for hypodermic injections and more particularly to mono-use syringes for hypodermic injections.
The use of mono-use "throw-away" syringes is known. Typically, "throw-away" syringes are packaged singularly in hermetically sealed wrappers. This simple type of packaging is practical and guarantees sterility of the syringe up until the moment that the syringe is used.
A problem associated with "throw-away" syringes is the possibility of reuse of the syringe for further injections. Because there is no assurance of hygienic conditions, repeated use of "throw-away" syringes increases risk of transmission of various types of diseases. The problems associated with the repeated use of "throw-away" syringes has been well documented in the case of intravenous drug abusers who commonly use syringes previously used by others.
The use of mono-use syringes having various mechanisms to render the syringe inoperable after a single use is also known. Examples of prior art mono-use syringes are illustrated in the following patents: Yerman U.S. Pat. No. 4,233,975 issued to on Nov. 18, 1980; Legendre U.S. Pat. No. 4,367,738 on Jan. 11, 1983; Butterfield U.S. Pat. No. 4,493,703 on Jan. 15, 1985; Hesse U.S. Pat. No. 4,731,068 on Mar. 15, 1988; and British Patent 2,197,792A published on June 2, 1988.
In the course of medical treatment, the intravenous nature of an injection is often important, as where the injected solution is toxic to muscle tissue or where the effectiveness of the treatment requires direct absorption of the injected solution by the blood stream. A commonly practiced technique used to verify the positive puncturing of a vein is by withdrawing a small amount of blood after the contents of the syringe have been injected.